The sizes of emission sources of deuterons and $\alpha$ particles were determined in minimum bias ${}^{16}\mathrm{O}-p$ collisions at $3.25A\mathrm{GeV}/c$ from the analysis of experimental one-dimensional correlation functions of these particles, based on a theoretical model assuming the simultaneous excitation and decay of sources (of identical particles), whose coordinates are distributed according to a Gaussian function. The peak was observed in the experimental correlation function of the pairs of $\alpha$ particles in the region of $q<25\mathrm{MeV}/c$, which was deduced to be due to decays of unstable ${}^8\mathrm{Be}$ and ${}^9\mathrm{B}$ nuclei at various kinetic energies. This result does not contradict the popular assumption of other authors about the existence of the $\alpha$-condensate state in the ${}^{16}\mathrm{O}$ nucleus since unstable ${}^8\mathrm{Be}$ and ${}^9\mathrm{B}$ nuclei themselves can probably be formed from decay of the $\alpha$-condensate state of the oxygen nucleus if such a state does exist.

The initial geometry effect on collective flows, which are inherited from initial projectile structure, is studied in relativistic heavy-ion collisions of ${}^{12}\mathrm{C}+{}^{197}\mathrm{Au}$ by using a multiphase transport model (AMPT). Elliptic flow ($v_2$) and triangular flow ($v_3$) which are significantly resulted from the chain and triangle structure of ${}^{12}\mathrm{C}$ with three-$\alpha$ clusters, respectively, in central ${}^{12}\mathrm{C}+{}^{197}\mathrm{Au}$ collisions are compared with the flow from the Woods-Saxon distribution of nucleons in ${}^{12}\mathrm{C}$. $v_3/v_2$ is proposed as a probe to distinguish the pattern of $\alpha$-clustered ${}^{12}\mathrm{C}$. This study demonstrates that the initial geometry of the collision zone inherited from nuclear structure can be explored by collective flow at the final stage in heavy-ion collisions.

We study time evolution of critical fluctuations of conserved charges near the QCD critical point in the context of relativistic heavy ion collisions. A stochastic diffusion equation is employed in order to describe the diffusion property of the critical fluctuation arising from the coupling of the order parameter field to conserved charges. We show that the diffusion property gives rise to a possibility of probing the early time fluctuations through the rapidity window dependence of the second-order cumulant and correlation function of conserved charges. It is pointed out that their nonmonotonic behaviors as functions of the rapidity interval are robust experimental signals for the existence of the critical enhancement around the QCD critical point.

In this paper we provide a quantum field theoretical study on the shear and bulk relaxation times. First, we find Kubo formulas for the shear and the bulk relaxation times, respectively. They are found by examining response functions of the stress-energy tensor. We use general properties of correlation functions and the gravitational Ward identity to parametrize analytical structures of the Green functions describing both sound and diffusion mode. We find that the hydrodynamic limits of the real parts of the respective energy-momentum tensor correlation functions provide us with the method of computing both the shear and bulk viscosity relaxation times. Next, we calculate the shear viscosity relaxation time using the diagrammatic approach in the Keldysh basis for the massless $\lambda {\varphi }^4$ theory. We derive a respective integral equation which enables us to compute $\eta {\tau }_{\pi }$ and then we extract the shear relaxation time. The relaxation time is shown to be inversely related to the thermal width as it should be.

I present a prediction of the $e^{\pm }$ elastic scattering cross-section ratio, $R_{e^{+}{e}^{-}}$, as determined using a new parametrization of the two-photon exchange (TPE) corrections to electron-proton elastic scattering cross section ${\sigma }_R$. The extracted ratio is compared to several previous phenomenological extractions, TPE hadronic calculations, and direct measurements from the comparison of electron and positron scattering. The TPE corrections and the ratio $R_{e^{+}{e}^{-}}$ show a clear change of sign at low $Q^2$, which is necessary to explain the high-$Q^2$ form factors discrepancy while being consistent with the known $Q^2\to 0$ limit. While my predictions are in generally good agreement with previous extractions, TPE hadronic calculations, and existing world data including the recent two measurements from the CLAS and VEPP-3 Novosibirsk experiments, they are larger than the new OLYMPUS measurements at larger $Q^2$ values.

We examine the two-photon exchange corrections to elastic electron-proton scattering within a dispersive approach, including contributions from both nucleon and $\mathrm{\Delta }$ intermediate states. The dispersive analysis avoids off-shell uncertainties inherent in traditional approaches based on direct evaluation of loop diagrams and guarantees the correct unitary behavior in the high-energy limit. Using empirical information on the electromagnetic nucleon elastic and $N\mathrm{\Delta }$ transition form factors, we compute the two-photon exchange corrections both algebraically and numerically. Results are compared with recent measurements of $e^{+}p$ to $e^{-}p$ cross section ratios from the CLAS, VEPP-3, and OLYMPUS experiments, as well as with polarization transfer observables.

Background: The recent accurate measurement of the mass of two pulsars close to or above $2{\mathrm{M}}_{\odot }$ has raised the question of whether such large pulsar masses allow for the existence of exotic degrees of freedom, such as hyperons, inside neutron stars.

Purpose: In the present work, we will investigate, within a phenomenological relativistic mean field approach, how the existing hypernuclei properties may constrain the neutron star equation of state and confront the neutron star maximum masses obtained with equations of state calibrated to hypernuclei properties with the astrophysical $2{\mathrm{M}}_{\odot }$ constraint.

Method: The study is performed using a relativistic mean field approach to describe both the hypernuclei and the neutron star equations of state. Unified equations of state are obtained. A set of five models that describe $2{\mathrm{M}}_{\odot }$ when only nucleonic degrees of freedom are employed. Some of these models also satisfy other well-established laboratory or theoretical constraints.

Results: The $\mathrm{\Lambda }$-meson couplings are determined for all the models considered, and the $\mathrm{\Lambda }$ potential in symmetric nuclear matter and $\mathrm{\Lambda }$ matter at saturation are calculated. Maximum neutron star masses are determined for two values of the $\mathrm{\Lambda }\text{−}\omega$ meson coupling, $g_{\omega \mathrm{\Lambda }}=2g_{\omega N}/3$ and $g_{\omega \mathrm{\Lambda }}=g_{\omega N}$, and a wide range of values for $g_{\varphi \mathrm{\Lambda }}$. Hyperonic stars with the complete baryonic octet are studied, restricting the coupling of the $\mathrm{\Sigma }$ and $\mathrm{\Xi }$ hyperons to the $\omega ,\rho ,$ and $\sigma$ mesons due to the lack of experimental data, and maximum star masses calculated.

Conclusions: We conclude that, within a phenomenological relativistic mean field approach, the currently available hypernuclei experimental data and the lack of constraints on the asymmetric equation of state of nuclear matter at high densities set only a limited number of constraints on the neutron star matter equation of state using the recent $2{\mathrm{M}}_{\odot }$ observations. It is shown that the $\mathrm{\Lambda }$ potential in symmetric nuclear matter takes a value of $\sim 30-32\mathrm{MeV}$ at saturation for the $g_{\omega \mathrm{\Lambda }}$ coupling given by the SU(6) symmetry, being of the order of the values generally used in the literature. On the other hand, the $\mathrm{\Lambda }$ potential in $\mathrm{\Lambda }$ matter varies between $-14$ and $-8$ MeV, taking for vector mesons couplings the SU(6) values, at variance with generally employed values between $-1$ and $-5$ MeV. If the SU(6) constraint is relaxed and the vector meson couplings to hyperons are kept to values not larger than those of nucleons, then values between $-13$ and $+9$ MeV are obtained.

We study the simultaneous effects of the symmetry energy and temperature on the crust-core transition of a magnetar. The dynamical and the thermodynamical spinodals are used to calculate the transition region within a relativistic mean-field approach for the equation of state. Quantizing magnetic fields with intensities in the range of $2\times {10}^{15}<B<5\times {10}^{16}\mathrm{G}$ are considered. Under these strong magnetic fields, the crust extension is very sensitive to the density dependence of the symmetry energy, and the properties that depend on the crust thickness could set a constraint on the equation of state. It is shown that the effect on the extension of the crust-core transition is washed out for temperatures above ${10}^9$ K. However, for temperatures below that value, a noticeable effect exists that grows as the temperature decreases and which should be taken into account when the evolution of magnetars is studied.

The shape transitions and shape coexistence in the Ge and Se isotopes are studied within the interacting boson model (IBM) with the microscopic input from a self-consistent mean-field calculation based on the Gogny-D1M energy density functional. The mean-field energy surface as a function of the quadrupole shape variables $\beta$ and $\gamma$, obtained from the constrained Hartree-Fock-Bogoliubov method, is mapped onto the expectation value of the IBM Hamiltonian with configuration mixing in the boson condensate state. The resultant Hamiltonian is used to compute excitation energies and electromagnetic properties of the selected nuclei ${}^{66–94}\mathrm{Ge}$ and ${}^{68–96}\mathrm{Se}$. Our calculation suggests that many nuclei exhibit $\gamma$ softness. Coexistence between prolate and oblate shapes, as well as between spherical and $\gamma$-soft shapes, is also observed. The method provides a reasonable description of the observed systematics of the excitation energy of the low-lying energy levels and transition strengths for nuclei below the neutron shell closure $N=50$, and provides predictions on the spectroscopy of neutron-rich Ge and Se isotopes with $52\le N\le 62$, where data are scarce or not available.

In this paper we present new results for prompt fission $\gamma$-ray spectral characteristics from the thermal neutron induced fission of ${}^{240}\mathrm{Pu}^{*}$. The measured spectra were unfolded by using the detectors' response functions, simulated with geant4. We obtained in average per fission a $\gamma$-ray multiplicity ${\overline{M}}_{\gamma }=(7.35\pm 0.12)$, a mean photon energy ${\overline{\epsilon }}_{\gamma }=(0.85\pm 0.02)$ MeV, and an average total energy released in fission ${\overline{E}}_{\gamma ,\mathrm{tot}}=(6.27\pm 0.11)$ MeV. Our results are in good agreement with historical data measured in the 1970s by Verbinski et al. and results from recent calculations in the framework of Monte Carlo Hauser–Feshbach models. Our measured average total energy is slightly smaller than the one deduced previously and present in evaluated data. From this we conclude that the ${}^{239}\mathrm{Pu}(n_{\mathrm{th}},f)$ reaction may be ruled out as possible source of $\gamma$ heating underestimation, when compared with benchmark calculations based on existing nuclear data.

The first step in any formalism that aims to connect a many-nucleon theory of nucleon-nucleus scattering and the concept of an optical model potential in the sense pioneered by Feshbach is to explain what is meant by the optical model wave function. By definition, this is a function of a single space coordinate plus a set of single-nucleon internal variables. This article gives a critique of the definition as it is frequently expressed in second quantization language and suggests a new definition which is more consistent with the requirements of antisymmetry and translational invariance. A modification of the time-dependent Green's function formalism is suggested.

Taking the Coulomb and proximity potential as the interaction barrier, we have studied the production cross section of probable projectile-target combinations for the synthesis of superheavy element ${}^{297}\mathrm{Ts}$. The cold reaction valley of ${}^{297}\mathrm{Ts}$ is studied to identify the possible projectile-target combinations for the synthesis of ${}^{297}\mathrm{Ts}$. The entrance channel Coulomb barrier, the quasifission barrier, and barrier positions for all these combinations are calculated. The fusion probability and survival probability of the excited compound nucleus are evaluated. At energies near and above the Coulomb barrier, the excitation function [capture, fusion, and evaporation residue (ER) cross sections] of these combinations leading to superheavy element (SHE) ${}^{297}\mathrm{Ts}$ is investigated. It is found that the production cross sections of ${}^{297}\mathrm{Ts}$ in cold fusion reactions are very small compared to hot fusion reactions. The combinations ${}^{40}\mathrm{S}+{}^{257}\mathrm{Md}, {}^{42}\mathrm{S}+{}^{255}\mathrm{Md}, {}^{43}\mathrm{Cl}+{}^{254}\mathrm{Fm}, {}^{44}\mathrm{Ar}+{}^{253}\mathrm{Es}, {}^{46}\mathrm{Ar}+{}^{251}\mathrm{Es}, {}^{48}\mathrm{Ca}+{}^{249}\mathrm{Bk}, {}^{50}\mathrm{Ca}+{}^{247}\mathrm{Bk}, {}^{67}\mathrm{Co}+{}^{230}\mathrm{Th}, {}^{68}\mathrm{Ni}+{}^{229}\mathrm{Ac}, {}^{70}\mathrm{Ni}+{}^{227}\mathrm{Ac}$, and ${}^{72}\mathrm{Ni}+{}^{225}\mathrm{Ac}$ are observed to be the most favorable projectile-target pairs for the production of SHE ${}^{297}\mathrm{Ts}$. Our calculated results are compared with experimental data and with other theoretical studies for the reaction ${}^{48}\mathrm{Ca}+{}^{249}\mathrm{Bk}$ leading to ${}^{297}\mathrm{Ts}$, and are in good agreement with experimental observation of Oganessian et al. Furthermore, the ER cross section for the synthesis of isotopes ${}^{291-296}\mathrm{Ts}$ and ${}^{298-299}\mathrm{Ts}$ using ${}^{48}\mathrm{Ca}$ induced reactions are studied. Among these isotopes, the isotope ${}^{298}\mathrm{Ts}$ has larger cross section in the 3n channel using the reaction ${}^{48}\mathrm{Ca}+{}^{250}\mathrm{Bk}$, and ${}^{299}\mathrm{Ts}$ has larger cross section in the 4n channel using the reaction ${}^{48}\mathrm{Ca}+{}^{251}\mathrm{Bk}$. Therefore, our theoretical predictions to produce isotopes of the element Ts will be helpful for future experiments, as the isotopes have not been synthesized so far.

We compute the in-medium partial decay widths of the bottomonium states to open bottom mesons $\left(B\overline{B}\right)$ using a field theoretical model for composite hadrons with quark constituents. These decay widths are calculated by using the explicit constructions for the bottomonium states and the open bottom mesons $(B$ and $\overline{B})$ and the quark-antiquark pair creation term of the free Dirac Hamiltonian written in terms of the constituent quark field operators. These decay widths in the hadronic medium are calculated as arising from the mass modifications of the bottomonium states and the $B$ and $\overline{B}$ mesons, obtained in a chiral effective model. The decay amplitude in the present model is multiplied with a strength parameter for the light quark pair creation, which is fitted from the observed vacuum partial decay width of the bottomonium state, $\mathrm{{\rm Y}}\left(4S\right)$ to $B\overline{B}$. The effects of the isospin asymmetry, the strangeness fraction of the hadronic matter on the decay widths, arising due to the mass modifications due to these effects, have also been studied. There is observed to be appreciable effects from density, and the effects from isospin asymmetry on the parital decay widths of $\mathrm{{\rm Y}}\to B\overline{B}$ are observed to be quite pronounced at high densities. These effects should show up in the asymmetric heavy ion collisions in Compressed baryonic matter (CBM) experiments planned at the future facility at FAIR. The study of the $\mathrm{{\rm Y}}$ states will, however, require access to energies higher than the energy regime planned at the CBM experiment. The density effects on the decay widths of the bottomonium states should show up in the production of these states, as well as in dilepton spectra at the Super Proton Synchrotron (SPS) energies.

We utilize the light-front relativistic quark model to predict the $3q$ core contribution to the electroexcitation of nucleon resonances of the $[70,1^{-}]$ multiplet on the proton and neutron at $Q^2<5{\mathrm{GeV}}^2$. The investigation is motivated by new experimental data from continuous electron beam accelerator facility large acceptance spectrometer on meson electroproduction for a wide range of the hadronic invariant mass including the full third nucleon resonance region up to $\sqrt{s}=1.8$ GeV. For the states $N\left(1520\right){\frac{3}{2}}^{-},N\left(1535\right){\frac{1}{2}}^{-}$, and $N\left(1675\right){\frac{5}{2}}^{-}$, experimental results on the electroexcitation amplitudes on the proton are available for a wide range of $Q^2$. This allowed us also to quantify the expected meson-baryon contributions to these amplitudes as a function of $Q^2$.

We discuss the effect of compression on Urca shells in the ocean and crust of accreting neutron stars, especially in superbursting sources. We find that Urca shells may be deviated from chemical equilibrium in neutron stars which accrete at several tenths of the local Eddington accretion rate. The deviation depends on the energy threshold of the parent and daughter nuclei, the transition strength, the temperature, and the local accretion rate. In a typical crust model of accreting neutron stars, the chemical departures range from a few tenths of $k_{B}T$ to tens of $k_{B}T$ for various Urca pairs. If the Urca shell can exist in crusts of accreting neutron stars, compression may enhance the net neutrino cooling rate by a factor of about $1\sim 2$ relative to the neutrino emissivity in chemical equilibrium. For some cases, such as Urca pairs with small energy thresholds and/or weak transition strength, the large chemical departure may result in net heating rather than cooling, although the released heat can be small. Strong Urca pairs in the deep crust are hard to be deviated even in neutron stars accreting at the local Eddington accretion rate.

We propose a general approach to describe spreading widths of monopole, dipole, and quadrupole giant resonances in heavy and superheavy spherical nuclei. Our approach is based on the ideas of the random matrix distribution of the coupling between one-phonon and two-phonon states generated in the random-phase approximation. We use the Skyrme interaction SLy4 as our model Hamiltonian to create a single-particle spectrum and to analyze excited states of the doubly magic nuclei ${}^{132}\mathrm{Sn}, {}^{208}\mathrm{Pb}$, and ${}^{310}126$. Our results demonstrate that the approach enables to us to describe a gross structure of the spreading widths of the giant resonances considered.

${}^{160}\mathrm{Gd}(n,n^{\prime }\gamma )$ experiments were performed with accelerator-produced monoenergetic neutrons. Excitation functions at neutron energies from 1.5 to 2.8 MeV aided in the placement of $\gamma$ rays in the level scheme and angular distributions at three neutron energies resulted in the determination of 28 excited-level lifetimes or limits in ${}^{160}\mathrm{Gd}$, including the lifetimes of several negative-parity levels attributed to octupole vibrations.

The production of $K^{*}{\left(892\right)}^0$ and $\varphi \left(1020\right)$ mesons in proton-proton ($pp$) and lead-lead (Pb-Pb) collisions at $\sqrt{s_{\mathit{NN}}}=2.76\mathrm{TeV}$ has been analyzed using a high luminosity data sample accumulated in 2011 with the ALICE detector at the Large Hadron Collider (LHC). Transverse momentum ($p_{\mathrm{T}}$) spectra have been measured for $K^{*}{\left(892\right)}^0$ and $\varphi \left(1020\right)$ mesons via their hadronic decay channels for $p_{\mathrm{T}}$ up to $20\mathrm{GeV}/c$. The measurements in $pp$ collisions have been compared to model calculations and used to determine the nuclear modification factor and particle ratios. The $K^{*}{\left(892\right)}^0/K$ ratio exhibits significant reduction from $pp$ to central Pb-Pb collisions, consistent with the suppression of the $K^{*}{\left(892\right)}^0$ yield at low $p_{\mathrm{T}}$ due to rescattering of its decay products in the hadronic phase. In central Pb-Pb collisions the $p_{\mathrm{T}}$ dependent $\varphi \left(1020\right)/\pi$ and $K^{*}{\left(892\right)}^0/\pi$ ratios show an enhancement over $pp$ collisions for $p_{\mathrm{T}}\approx 3\mathrm{GeV}/c$, consistent with previous observations of strong radial flow. At high $p_{\mathrm{T}}$, particle ratios in Pb-Pb collisions are similar to those measured in $pp$ collisions. In central Pb-Pb collisions, the production of $K^{*}{\left(892\right)}^0$ and $\varphi \left(1020\right)$ mesons is suppressed for $p_{\mathrm{T}}>8\mathrm{GeV}/c$. This suppression is similar to that of charged pions, kaons, and protons, indicating that the suppression does not depend on particle mass or flavor in the light quark sector.

The total cross section, the intermediate mass fragment (IMF) production cross section, and the cross section for the formation of light particles (LPs) for the decay of compound system ${}^{56}\mathrm{Ni}^{*}$ formed through the entrance channel ${}^{32}\mathrm{S}+{}^{24}\mathrm{Mg}$ have been evaluated by taking the scattering potential as the sum of deformed Coulomb and deformed nuclear proximity potentials, for various $E_{\mathrm{c}.\mathrm{m}.}$ values. The computed results have been compared with the available experimental data of total cross section corresponding to $E_{\mathrm{c}.\mathrm{m}.}=60.5$ and 51.6 MeV for the entrance channel ${}^{32}\mathrm{S}+{}^{24}\mathrm{Mg}$, which were found to be in good agreement. The experimental values for the LP production cross section and IMF cross section for the channel ${}^{32}\mathrm{S}+{}^{24}\mathrm{Mg}$ were also found to agree with our calculations. Hence we have extended our studies and have thus computed the total cross section, IMF cross section, and LP cross section for the decay of ${}^{56}\mathrm{Ni}^{*}$ formed through the other three entrance channels ${}^{36}\mathrm{Ar}+{}^{20}\mathrm{Ne},{}^{40}\mathrm{Ca}+{}^{16}\mathrm{O}$, and ${}^{28}\mathrm{Si}+{}^{28}\mathrm{Si}$ with different $E_{\mathrm{c}.\mathrm{m}.}$ values. Hence, we hope that our predictions on the evaluations of the IMF cross sections and the LP cross sections for the decay of ${}^{56}\mathrm{Ni}^{*}$ formed through these three channels can be used for further experimental studies.